The present invention relates to a thin film magnetic head which is used for writing and reading information to and from a magnetic recording medium.
A thin film magnetic head includes a thin film magnetic core around which is wound a conductive coil. Conventional thin film magnetic heads exhibit an operational defect, known as "wiggles" to those skilled in the art. This defect may become more pronounced after a write current, applied to the coil during a write operation, changes the core magnetization (i.e., the magnetic domain patterns of the magnetic core), when such change persists after termination of the write current. In accordance with the "wiggles" phenomenon, when a magnetic field is applied from a recorded magnetic medium to the magnetic core in a read operation, there is a disturbance of the read signal from the coil caused by noise generated with a change in the magnetic core magnetization.
To help prevent this defect, it is necessary to stabilize the magnetic core magnetization against the strong magnetic field applied to the magnetic core during a write operation, as is proposed by K. Ohashi in the document entitled "Mechanism of 90.degree. Wall Motion in Thin Film Heads", IEEE Transactions on Magnetics, Vol. MAG-21, No. 5, pp, 1581-1583, September, 1985. To this end, the conventional thin film magnetic head is required to have a magnetic core whose contents (e.g., Ni, Fe, and so on) by weight percentages are strictly controlled to be within certain ranges, and whose axis of easy magnetization is at a right angle with respect to the applied magnetic field. As to the latter, i.e., the angle of the easy magnetization axis, to obtain the required angular relationship, strict control of the physical characteristic of almost all the magnetic head components is required. These components include the protective layer, the insulating layer, the conductive coil, etc. of the magnetic head. Conflicting with these requirements is the fact that the weight percentage control and the physical characteristic control have certain limits due to manufacturing limitations, so that the defect called "wiggles" is difficult to reduce.